The Radiation Therapy Oncology Group (R.T.O.G.) is a group of 41 collaborating institutions formed to evaluate cancer treatment protocols in prospective controlled randomized clinical trials. Cooperative studies are undertaken to advance knowledge in the curative and palliative management of cancer. Conducting such investigations within individual institutions is restrictive because of limited patient material. The pooling of patient material by member institutions overcomes this limitation. Treatment protocols subjected to study involve various cancers and their multi-disciplinary management by radiotherapy, surgery and chemotherapy. The protocols are under the strict supervision of the Radiologic Physics Center with data analysis conducted by the Biostatistical Center of the Group. Long-term data will be collected with regard to patient survival, quality of survival and complications of treatment.